models.py

```python
class MyUser(AbstractUser):
    idstaff = models.CharField(max_length=255)

    class Meta:
        db_table = 'myuser'
        swappable = 'AUTH_USER_MODEL'
```

admin.py

```python
class MyAdmin(UserAdmin):
    fieldsets = ((None, {'fields': ('iduser')}),) + UserAdmin.fieldsets
    add_fieldsets = (
        (None, {
            'classes': ('wide',),
            'fields': (
                'iduser',
                'username',
                'email',
                "first_name", "last_name",
                'password1', 'password2',
            ),
        }),
    )
```